An artist's scupting of A. afarensis, based on the earlier Lucy skeleton. (Source: Educa Madrid)

The bones of "Big Man" (Source: Y. Haile Selassie et al./PNAS 2010)

"Whatever we’ve been saying about afarensis based on Lucy was mostly wrong."

Much like the revolution of modern astronomy in the late 1400s and early 1500s dissolved the notion that the Sun revolved around the Earth, a renaissance in paleontology is dissolving virtually any doubt that remained about man's origins. Another new discovery has just been completed, the latest of several high profile publications over only the last year.

The new skeleton is a male Australopithecus afarensis, which has been discovered in Ethiopia’s Afar region. The skeleton joins the celebrated "Lucy" skeleton, unearthed by paleoanthropologists in 1974, and a child skeleton unearthed last year.

The ancient male, an ancestor of modern man, lived approximately 3.6 million years ago in the plains of Eastern Africa, according to several dating techniques. Yohannes Haile-Selassie of the Cleveland Museum of Natural History, who led the team, says the skeleton offers some major new insights into the species.

The skeleton has been nicknamed "Big Man" as it towers at 5 to 5½ feet tall over the much shorter 3½-foot-tall Lucy, who lived 3.2 million years ago. That large height deviation raises questions over which of the specimen is the norm in terms of height. The new skeleton was unearthed between 2005 and 2008 at a dig site only 48 km from where Lucy was found.

The skeleton also reveals new insights into the bone structure of the species. Big Man's 32 discovered bones reveal long legs, a narrow chest, and a inwardly curving back. All of these indicate that he walked much like a human and enjoyed a ground-based lifestyle. This is very different from the awkward gait that Lucy was thought to have. Lucy also had been thought to climb trees a great deal.

The shoulder blade of Big Man is quite different from chimpanzees or gorillas. And the ribs also appear human-like. All of these factors indicate a far different chest shape than the chimplike, funnel-shaped chest that reconstructions of the Lucy skeleton indicated.

Professor Haile-Selassie states, "Whatever we’ve been saying about afarensis based on Lucy was mostly wrong. The skeletal framework to enable efficient two-legged walking was established by the time her species had evolved."

Carol Ward of the University of Missouri in Columbia seems to agree with these conclusions, stating, "This beautiful afarensis specimen confirms the unique skeletal shape of this species at a larger size than Lucy, in what appears to be a male."

While the discovery may have cleared up debate about whether Lucy was more chimplike or humanlike, the debate about gait is sure to continue. Harvard University anthropologist Daniel Lieberman states, "There’s nothing special I can see on this new find that will change anyone’s opinion."

Anthropologist Owen Lovejoy of Kent State University, however, believes that the discovery shows Big Man to be a good runner, which could have made the 3.6-million-year-old footprints found more than 30 years ago at Laetoli, Tanzania. Among the evidence supporting this hypothesis are Big Man's pelvis supported humanlike hamstring muscles and human-like arched feet.

The full study on the Big Man discovery is published here in the journal Proceedings of the National Academy of Sciences.

A separate 3.3 million year old skeleton of a 3-year-old baby female A. afarensis was presented four years ago. Nicknamed "Selam" (the word for "peace" in several African languages), the near-complete skeleton was found in 2000 south of the Awash river by a team led by Zeresenay Alemseged of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.

The paper on that discovery was published in a 2006 edition of Nature and can be found here.

These discoveries add to the aforementioned recent discovery of "Ardi", the discovery of Australopithecus sediba, and the completion of an early draft of the Neanderthal genome. All of these wonderful discoveries have helped to blow away the fog of uncertainty surrounding human evolution and offered a much clearer picture of how man arrived at its current form after a slow process of evolution that took millions of years.

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